Catalyst converter

ABSTRACT

A catalyst converter for purifying the exhaust gas from an internal combustion engine, including a catalyst holder disposed in a casing connected at one end to an exhaust manifold of the engine and at the other end to an exhaust pipe, members for defining passages for the exhaust gas in the casing, and valves in said casing provided in association with said members, said valves being operated to change the direction of the exhaust gas flow in the casing in accordance with the temperature in the catalyst holder.

This is a division of application Ser. No. 448,348, filed on Mar. 5,1974.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a device for purifying exhaust gas from aninternal combustion engine, said exhaust gas being one of atmosphericpollution sources, and more particularly to a catalyst converter forpurifying the exhaust gas by using catalysts.

The mixture gas of air with fuel to be fed in cylinders of an internalcombustion engine is subjected to combustion and explosion within saidcylinders, followed by discharging as an exhaust gas outside thecylinders. Such an exhaust gas contains incomplete-combustion gases suchas unburned hydrocarbons, carbon monoxide and the like and toxic gasessuch as NOx produced due to combustion at an elevated temperature.

By the term "a catalyst converter" as used herein is meant a converterwhich uses catalysts for treatment of an exhaust gas, said treatmentcomprising the steps of oxidation, reduction, filtration or adsorptionof toxic gases contained in exhaust gas, followed by discharge ofexhaust gas into atmosphere.

2. Description of the Prior Art

One of the conventional type catalyst converters of the prior art isprovided with a member which supports a catalyst holder disposedsubstantially in the center of a casing having inlet and outlet pipes,with its opposite side portions of said holder being in engagement withthe inner walls of said casing, and which defines within the casing apassage for exhaust gas. Another of the conventional type catalystconverters is provided with a member which is located within the casingin concentric relation therewith as in the preceding case and whichcontains honeycomb catalysts therein and defines a passage for exhaustgas. Such a catalyst converter is so designed as to maintain constantthe flow passage of exhaust gas within the catalyst converter and not toextremely lower the output of an engine during the normal operationthereof, thereby achieving efficient purifying action of exhaust gas.

In general, as reported on LA No. 4 mode test, the adverse or toxiccomponents of the exhaust gas discharged during operational conditionscovering from the starting, warming-up and the subsequent phases of runof an internal combustion engine are particularly contained in a greatamount in the exhaust gas which is discharged for a period from thestarting of an engine to the completion of warming-up period.

On the other hand, since the catalysts contained in catalyst convertersused with internal combustion engine for purifying said exhaust gas areheated to an activating temperature, principally by means of exhaust gaspassing through the catalysts from the internal combustion engine, thetemperature of catalysts after the warming-up operation of the enginewill reach almost the activating temperature of the catalysts. For thisreason, even if a conventional type catalysts converter is provided forthe internal combustion engine, the temperature of the catalystscontained in the catalyst converter is maintained below their activatingtemperature, i.e. before the warming-up run of the internal combustionengine, the converter will fail to achieve sufficient purifying effecton toxic gases, such that the internal combustion engine discharges agreat amount of toxic gases into the atmosphere. Accordingly, in orderto enhance the purifying action of a catalyst converter before thewarming-up run of the internal combustion engine, it is necessary torapidly raise the temperature of catalysts.

To this end, an attempt may be proposed, in which the cross sectionalarea of the catalysts layer passing exhaust gas therethrough is reducedso as to minimize the radiation of heat therefrom for the purpose ofimparting the heat contained in the exhaust gas to catalysts, therebyaccelerating the rate of the temperature rise of the catalysts. However,there will arise a problem that the pressure of the exhaust gas isincreased due to such a high level of the load application, withaccompanied excessive loss in power output of an engine.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to provide acatalyst converter which can purify exhaust gas to a satisfactoryextent, even before the warming-up run of an internal combustion engine,while preventing the drop in power output of the engine.

It is a further object of the invention to provide a catalyst converterwhich can purify the exhaust gas from an internal combustion engine,even before the warming-up run of an engine.

It is a still further object of the invention to provide a catalystconverter which will not lower the power output even at the time of highloading condition of an internal combustion engine.

It is a yet further object of the invention to provide a catalystconverter which may maintain constant the effective amount of thecatalyst to be used before and after the warming-up run of an internalcombustion engine.

According to the present invention, there is provided a catalystconverter comprising a member which provides the flow passages of thegas passing through a converter casing, and valves associated with saidmember, whereby the opening and closing of said valve commensurate withthe temperature of the catalysts contained within the converter changesthe flow passages of the exhaust gas within said converter.

Before the warming-up run of the internal combustion engine, said valveis closed so as to reduce the cross sectional area of the catalystlayer, through which exhaust gas passes to thereby increase theresidence time and rapidly raise the temperature of catalysts up to theactivating temperature range. On the other hand, after the warming-uprun of the internal combustion engine, said valve is opened so as toincrease said cross sectional area to thereby prevent the loss in powerdue to increases in exhaust gas back pressure. This permits rapidpurification of an exhaust gas to a great extent, even before thewarming-up run of the internal combustion engine, as well as preventionof decrease in power output at the time of high level of loadapplication to the engine, even after the warming-up run of the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a catalyst converter according tothe present invention;

FIG. 2 is a cross sectional view taken along the line 2--2 of FIG. 1;

FIG. 3 is a cross sectional view of another embodiment of the presentinvention;

FIG. 4 is a cross sectional view taken along the line 4--4 of FIG. 3;

FIG. 5 and FIG. 6 are cross sectional views illustrating the operationsof catalyst converter as shown in FIGS. 2, 3 and 4;

FIGS. 7 and 9 are cross sectional views of the other embodiments of thepresent invention; and

FIG. 8 is a cross sectional view taken along the line 8--8 of FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A converter 10 as shown in FIG. 1 includes a casing 12, a catalystholder 14 disposed substantially in the center of said casing therein,and spaced along its top and bottom from the inner wall of said casing,with the opposite side portions of said holder being in engagement withthe respective inner side walls of said casing, said holder containingthe catalyst 13. The converter 10 also includes two sheets of shieldingor baffle plates 16 and 18 adapted to transversely close the oppositeends of said holder, and two valves 20 and 22. The casing 12 is providedat its one end with an inlet pipe 24 connected with an exhaust manifold(not shown) of an internal combustion engine and at the other end withan outlet pipe 26 connected with an exhaust pipe (not shown). Theshielding plates or baffles 16 and 18 are adapted to close the oppositeends of the holder 14. The shielding or baffle plate 16 extends acrossand is contoured with the bottom wall of the casing 12, as shown in FIG.2, to define the front wall of the lower space or outlet plenum 28 andan enclosing side wall for the permeable catalyst holder 14. The plate16 is spaced along its top edge from the inside of the top wall of thecasing 12 to provide therewith the front opening of the upper space orinlet plenum 30. The plate 16 thus supports and closes the front end ofthe catalyst holder 14, leaving its top permeable surface incommunication with the inlet plenum 30.

The other end of the catalyst holder 14 is closed and supported by theshielding or baffle plate 18 that extends across and is contoured withthe top wall of the catalyst holder 14, to define the rear wall of theupper space or inlet plenum 30 and an enclosing side wall for the otherend of the catalyst holder 14. The plate 18 is spaced along its bottomedge from the inside bottom wall of the casing 12 to provide therewiththe rear opening of the lower space or outlet plenum 28. The plate 18thus supports and closes the rear end of the catalyst holder 14, leavingits bottom permeable surface in communication with the outlet plenum 28.The two valves 20 and 22 are provided intermediate said first shieldingplate 16 and the second shielding plate 18. In addition, the first valve20 which is adapted to close the space 30 is positioned closer to theshielding plate 16 than is the second valve which is adapted to closethe space 28.

Thus in the closed position of the valves 20 and 22, the exhaust gasesentering the inlet pipe 24 are directed in a circuitous path of longerresidence time through the converter 12 in that the shielding plate 16directs the gases through the catalyst holder 14 into the space oroutlet plenum 28, where the valve 22 changes the path back through thecatalyst holder into the space or inlet plenum 30, downstream of thevalve 20, only to be diverted again by the shielding plate 18 backthrough the catalyst holder 14 into the space 28 downstream of the valve22, and thence into the outlet pipe 26. In the open position the valves20 and 22 the exhaust gases are directed by the shielding plates 16 and18 in a single pass from the space 30 through the catalyst holder 14into the space 28 with shorter residence time.

According to the embodiment as shown in FIG. 1, the valves 20 and 22 areformed of plates and supported on shafts 32 and 34 journaled in thecasing 12, respectively, while the operating mechanism for the valves 20and 22 includes a pair of link members 36 and 38, and 40 and 42, springs44 and 46, and first and second diaphragm mechanisms 48 and 50, therespective diaphragm being connected with a solenoid valve-actuatingdevice 52. The valve-actuating device 52 is adapted to receive throughan amplifying circuit 58 a signal from an operating circuit 56 connectedto a thermocouple 54 provided within the casing 12, and the device 52 isoperated by the signal thus received. Connected to the link members 36and 40 are springs 44 and 46 which are rigidly affixed at their ends tothe outer wall of the casing 12, while the link members 38 and 42 areconnected through connecting rods 60 and 62 to diaphragms 64 and 66 ofthe first and second diaphragm mechanisms 48 and 50. The solenoidvalve-actuating device 52 is provided with a casing 68, a solenoid coil69 located within the casing 68, and a plunger 70 disposed in concentricrelation with the coil 69. The casing 68 is provided with a port 71communicating with diaphragm mechanisms 48 and 50 and with a port 72communicating with a suction pipe (not shown), while the valve 73 isadapted to close the port 72 through an air tight seal 74 provided onthe periphery of the port 72 or brings the ports 71 and 72 incommunicating with each other, or otherwise shields the interior of thecasing from atmosphere through an air-tight seal 75 provided at one endof the coil 69. The diaphragm chambers 76 and 78 of the first and seconddiaphragm mechanisms 48 and 50 are each in communication with the port71 of the solenoid valve-actuating device through pipes 81 and 82 andthrough a coupling pipe 83 and a pipe 84 coupled with the coupling pipe83.

The thermocouple 54 is connected through lead wires 85 and 86 to theoperating circuit 56 which in turn is connected through lead wires 87and 88 to the amplifying circuit 58 which is then connected through leadwires 89 and 90 to the solenoid coil 69 of the valve-actuating device52.

Referring now to FIG. 2 showing an embodiment of securing the valves 20and 22 to the casing 12, the valve 20 is rigidly journaled on a shaft 32along the length thereof, said shaft being supported at its ends by thebushings 91 in the bearings 92 mounted on the casing 12, while anair-tight seal 93 is provided between the shaft 32 and the bearing 92.The valve 20 is adapted to close the exhaust gas inlet plenum 30 in itsgreater part, thereby changing the flowing passage of the exhaust gaspassing through the inlet plenum 30.

The thermocouple 54 provided within the catalyst holder 14 is adapted toconvert the heat of the catalyst 13 within the holder 14 into anelectrical signal to thereby feed same to the operating circuit 56.Depending on whether the signal representing the temperature of thecatalyst 13 is above or below the activating temperature, the circuit 56will transmit a signal through the amplifying circuit 58 to the solenoidcoil 69, thereby shifting the plunger 70 of the valve-actuating device52 to the right or to the left as shown. The rightward shifting of theplunger 70 (as viewed in FIG. 1) will close the port 72 communicatingwith the suction pipe, thereby bringing the port 71 in communicationwith atmosphere through the space between the casing 68 and plunger 70,while the leftward shifting of the plunger 70 will convey the negativepressure in the suction pipe through the port 72 and pipes 81, 82 and 84to the diaphragm chambers 76 and 78 of the first and second diaphragmmechanisms 48 and 50. The rightward shifting of the respectivediaphragms 64 and 66 of the diaphragm mechanisms 48 and 50 in thedrawing will cause the rightward movement of the connecting rods 60 and62 along with the link members 38 and 42 against the tension of springs44 and 46, thereby maintaining the valves 20 and 22 in positions asshown by solid lines in the drawing. This is the case when the catalyst13 is not yet warmed up, i.e. the temperature of the catalyst 13 isbelow the activating temperature. On the other hand, in case thedetected temperature by the thermocouple 54 goes above the activatingtemperature of the catalysts 13, the solenoid valve 73 will move to theright to bring the port 71 into communication with atmosphere, whereby,due to the restoring forces of the first and second diaphragm mechanisms48 and 50 as well as springs 44 and 46, the valves 20 and 22 aremaintained in positions shown by broken lines in the drawing.

In passing, the material of the first and second valves may be such asis deformable due to ambient temperature at valves. FIGS. 3 and 4illustrate first and second valves 94, 96 made of bimetal. In case thetemperature within the casing 12 is below the activating temperature,first and second valves 94 and 96 close the plenums 30 and 28 betweenthe inner wall of the casing 12 and the catalyst holder 14, while incase the temperature within the casing 12 is over the activatingtemperature, the valves 94 and 96 will open plenums 30 and 28,respectively. The valves 94 and 96 are secured through rivets 98 and 100to the inner wall of the casing 12. Upon starting of the internalcombustion engine, the temperature within the casing 12 is low such thatthe first and second valves 94 and 96 maintain the positions shown bysolid lines in the drawing, respectively. In the process of thewarming-up run of the engine, i.e., up to the activating temperature,the heat contained in the exhaust gas is absorbed into catalyst 13, suchthat the temperature within the casing 12 will not rise to a greatextent, whereby the valves 94 and 96 will be maintained in saidpositions. However, after the warming-up run of the engine, i.e., whenthe temperature at catalyst 13 is raised to the activating temperature,then the temperature within the casing 12 will be extremely raised, suchthat the first and second valves 94 and 96 made of bimetal will bedeformed as shown by the broken lines in the drawing. As is clear fromthe foregoing, the use of the first and second valves made of bimetalmay obviate the use of the operating mechanisms as shown in FIGS. 1 and2.

The first and second valves 20, 22 and 94, 96 for the catalystconverters as shown in FIGS. 1, 2 and 3,4 are maintained in positions asshown by solid lines in FIG. 5, at the time of starting and beforewarming-up run of the internal combustion engine. For this reason, themajority of the exhaust gas fed into the casing 12 is passed, in theorders shown by arrows, through the casing 12. More particularly, theexhaust gas fed through the inlet pipe is directed by the shieldingplate 16 into the exhaust gas inlet plenum 30 between the casing 12 andholder 14, then transferred through catalyst 13 with the aid of saidfirst valve 20 (or 94) into the exhaust gas outlet plenum 28. Further,the exhaust gas is passed through catalyst 13 with the aid of saidsecond valve 22 (or 96), then back into the exhaust gas inlet plenum 30through the catalyst 13 with the aid of the baffle plate 18, then intothe exhaust gas outlet plenum 28 and to the outlet pipe. In other words,the exhaust gas is passed through catalyst 13 three times, i.e.,according to so called three pass system.

On the other hand, after the warming-up run of the engine, as shown inFIG. 6, the first and second valves 20 (94) and 22 (96) are at rest onthe inner wall of the casing 12 in close contact therewith, and thus theexhaust gas within the casing 12 is passed through the catalyst 13 justonce, i.e., according to one way system.

The cross sectional area of the catalyst layer, through which theexhaust gas passes, may be reduced to one third by means of the firstand second valves, comparing before and after the warming-up run of theengine. Accordingly, during warm-up of the engine where the exhaust gascontains the greatest amount of undesirable contaminants, the catalysticconverter of this invention provides for repeated successive contacts ofthe exhaust gas within the catalytic zone and correspondingly greaterresidence times therein.

FIGS. 7, 8 and 9 show the embodiments of a honeycomb catalyst converter.The honeycomb catalyst converter 110 is provided with the radiallyspaced tubular members 120 and 122 which define a plurality of passagesor plenum 114 116 and 118 provided within the casing 112 in concentricrelation therewith, with the honeycomb catalyst 124 being contained ineach of said plenums 114, 116 and 118. The tubular members 120 and 122are made of the same material as that of the casing 112. The casing 112is provided at its one end with an exhaust gas inlet pipe 126 connectedwith an exhaust manifold (not shown) and at the other end with anexhaust gas outlet pipe 128 connected with an exhaust pipe (not shown).The innermost passage 114 of the plurality of passages is connected tothe inlet pipe 126 by a bypass pipe 130, and there is provided, as anextension of the tubular member 122, an enclosure 132 which extends inspaced relationship with the inner wall of the casing 112 andcommunicates the innermost passage 114 with the outer next most passage116 with respect to the passage 114 in a position close to the outletpipe 128. Furthermore, the converter 110 is provided with a valve 134positioned in the rear of the branch-point of the bypass pipe 130, i.e.,to the right with respect to the branch-point as viewed in FIG. 7.Furthermore, a valve 136 is provided within the enclosure 132,permitting the communcication of the passages 114 and 116 with theoutlet pipe 128 when in the open position as shown in FIG. 9 andprevents such communication when in the closed position of FIG. 7. FIG.8 shows the concentric relationship of these parts. The vane-type valves134 and 136 are supported on shafts 138 (journalled across the exhaustgas inlet pipe 126) and 140 which is journaled in the casing 112 or theenclosure 132. The valves 134 and 136 are operated by the mechanism asshown in FIG. 1, commensurate to the temperature at the honeycombcatalyst 124.

Before the warming-up run of the internal combustion engine, the firstvalve 134 closes the passage at a point in the rear (downstream) of thebranch-point of the bypass pipe in the inlet pipe 126, i.e., the passagedownstream of the inlet 126, while the second valve 136 blocks thecommunication of the passages 114 and 116 with the outlet pipe 128. Withsuch an arrangement, exhaust gas introduced through the inlet pipe 126in a direction shown by an arrow in FIG. 7 flows through bypass pipe 130as well as innermost passage 114 toward the outlet pipe 128. The exhaustgas from the passage 114 flows, due to the closed position of the valve135 (FIG. 7) enclosure 132, back through the passage 116 providedoutwardly of the passage 114 in surrounding relation, toward the inletpipe 126. The exhaust gas from the passage 116 flows through the chamberdefined by closing the first valve 134 in the passage leading to theinlet pipe 126, then through the outermost concentric passage 118 towardthe outlet pipe 128, and is then discharged from the outlet pipe. Thusthe exhaust gas is subjected to contact with the catalyst 124 for alonger residence time.

On the other hand, after warming-up run, i.e., when the temperature atthe honeycomb catalysts reaches the activating temperature, then thefirst and second valves 134 and 136 open the inlet pipe 126 as shown inFIG. 9, thereby opening the passage of the enclosure 132 to the outletpipe 128. This causes part of the exhaust gas from the inlet pipe 126 toflow, as shown by arrows in FIG. 9, into the bypass pipe 130 as in thecase prior to the warming-up run of the engine, and then into theinnermost passage 114, while the other part of the exhaust gas isintroduced directly in the outer passages 116 and 118, then through thepassages 114, 116 and 118 in the same manner as in the preceding caseaccording to one way flow system and then through the outlet pipe 128out to atmosphere.

Also in the embodiment of the honeycomb catalyst converter, the crosssectional area of the catalyst layer, through which the exhaust gaspasses, may be reduced to one third, when comparing it before and afterthe warming-up run of an engine, while the exhaust gas through thecatalyst then flows through the passage provided outwardly of theinnermost passage, whereby the exhaust gas will heat the circumferenceof the innermost passage to thereby enhancing the warming-up run.

According to the present invention, the amount of catalyst which is usedefficiently before and after the warming-up run of the engine may bemaintained constant, and the temperature at the catalyst in the processof the warming-up run of an engine may be further rapidly raised to theactivating temperature as compared with the conventional case, whereby agreat amount of toxic gas discharged from the internal combustion enginein the process of the warming-up run thereof may be purified andprevented to be discharged as toxic gas to atmosphere.

What is claimed is:
 1. A catalytic converter for use in purifyingexhaust gases from an internal combustion engine comprising:an elongatedwalled casing having an inlet conduit at one end and an outlet conduitat the other end; at least a pair of spaced concentric tubular membersaxially disposed within said casing which form a plurality of annularpassages for gas flow therethrough; a honeycomb catalyst member disposedin said annular passages; one of said tubular members extendingcentrally of said casing and another of said tubular members beingspaced outside of said central tubular member and spaced from the insidewall of said casing; a bypass conduit connected to and communicatingwith said inlet conduit exterior of said casing at one end of saidbypass conduit and connected to said central tubular member at the otherend of said bypass conduit; said other tubular member having a tubularextension disposed from its end adjacent said outlet conduit andencompassing the outlet end of said tubular members; a first normallyclosed valve means disposed within said inlet conduit between itsjuncture with said bypass conduit and said casing; a second normallyclosed valve means disposed within said extension; temperature sensingmeans located within said catalyst member; and control means operativelyconnected to said valve means and responsive to said temperature sensingmeans to simultaneously open said valve means and decrease the residencetime of said gases within said catalyst as a function of saidtemperature.
 2. A catalytic converter in accordance with claim 1 inwhich:said valve means each comprise a vane member; a pivot shaftsupported by said inlet conduit and affixed to said vane member of saidfirst valve means; a pivot shaft supported by said tubular extension andaffixed to said vane member of said second valve means; lever meansaffixed to one end of each of said pivot shafts; means biasing saidlever means to rotate said pivot shafts and respective vane members topositions blocking the passage of exhaust gases at their respectivepositions; and means responsive to the temperature within said catalystmember and operatively connected to each of said biasing means to pivotsaid lever means and said vane members to the open position upon anincrease in said temperature.